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list.h

#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H

/*
 * Simple doubly linked list implementation.
 *
 * Some of the internal functions ("__xxx") are useful when
 * manipulating whole lists rather than single entries, as
 * sometimes we already know the next/prev entries and we can
 * generate better code by using them directly rather than
 * using the generic single-entry routines.
 */

struct list_head {
      struct list_head *next, *prev;
};

#define LIST_HEAD_INIT(name) { &(name), &(name) }

#define LIST_HEAD(name) \
      struct list_head name = LIST_HEAD_INIT(name)

#define INIT_LIST_HEAD(ptr) do { \
      (ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)

/*
 * Insert a new entry between two known consecutive entries. 
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static __inline__ void __list_add(struct list_head * new,
      struct list_head * prev,
      struct list_head * next)
{
      next->prev = new;
      new->next = next;
      new->prev = prev;
      prev->next = new;
}

/*
 * Insert a new entry after the specified head..
 */
static __inline__ void list_add(struct list_head *new, struct list_head *head)
{
      __list_add(new, head, head->next);
}

/*
 * Insert a new entry before the specified head..
 */
static __inline__ void list_add_tail(struct list_head *new, struct list_head *head)
{
      __list_add(new, head->prev, head);
}

/*
 * Delete a list entry by making the prev/next entries
 * point to each other.
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static __inline__ void __list_del(struct list_head * prev,
                          struct list_head * next)
{
      next->prev = prev;
      prev->next = next;
}

static __inline__ void list_del(struct list_head *entry)
{
      __list_del(entry->prev, entry->next);
}

static __inline__ int list_empty(struct list_head *head)
{
      return head->next == head;
}

/*
 * Splice in "list" into "head"
 */
static __inline__ void list_splice(struct list_head *list, struct list_head *head)
{
      struct list_head *first = list->next;

      if (first != list) {
            struct list_head *last = list->prev;
            struct list_head *at = head->next;

            first->prev = head;
            head->next = first;

            last->next = at;
            at->prev = last;
      }
}

#define list_entry(ptr, type, member) \
      ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

#endif

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